Answer:
Power will be 0.2023 watt 
And when amplitude is halved then power will be 0.0505 watt
Explanation:
We have given mass of the Piano wire m = 2.60 gram = 0.0026 kg 
Length of wire l = 84 cm = 0.84 m 
So mass density 
Tension in the wire T = 25 N 
Frequency f = 120 Hz
So angular frequency 
And amplitude A = 1.6 mm = 0.0016 m 
We have to find the generated power 
Power is given by 
From the relation we can see that power 
So if amplitude is halved then power will be  times
 times 
So power will be equal to 
 
        
             
        
        
        
The EMF of the battery includes the force to to drive across its internal resistance. the total resistance:  
R = internal resistance r + resistance connected rv 
R = r + rv  
Now find the current:  
V 1= IR 
I = R / V1  
find the voltage at the battery terminal (which is net of internal resistance) using  
V 2= IR  
So the voltage at the terminal is:  
V = V2 - V1  
This is the potential difference vmeter measured by the voltmeter.
        
                    
             
        
        
        
Answer: C is right
Explanation: Most of the sound waves are reflected back but waves passing opening will speread to all directions outside because of diffraction
 
        
             
        
        
        
Answer:
A
The upthrust on a floating body is in upwards direction and is equal to the weight of the liquid displaced
B
The upthrust is directly proportional to the density of the liquid in which the solid is immersed
C
The upthrust is directly proportional to the volume of the fluid displaced by a solid
The upthrust acts on the body in upward direction at the center of buoyancy.
Upthrust is equal to the weight of liquid displaced by object and weight of liquid will depend on its density.
Upthrust is F=Vρg ,where V is the volume of liquid displaced and ρ is the density of fluid.
The total lateral pressure acting on an immersed object on one side is equal and in opposite direction to the total lateral pressure acting on the other side.